Yara, the best you can do is contact Canvas Support at your school and ask that they look into it and provide the info to your teacher.

If you’re not sure how to contact support check your course syllabus and/or you should also be able to click on the Help link in Canvas and Report a Problem. When you do this make sure and provide the date and time that you tried to submit the assignment and the exact course and name of the assignment.

Support can’t verify what tried to do, they can only verify the date and time and that you were on the assignment page. If it matches what you say happened then it adds credibility to your story and might influence your teacher. I would also encourage you to not reopen your assignment file or do anything to it. Instead email or Inbox message it to your teacher with information about what happened.